1. Field of the Invention
The present invention relates generally to a drill which has at least one fluid channel for the cooling and/or lubrication of the drilling process. In conventional drilling tools or drills, the coolant-lubricant oil is supplied by means of at least one fluid channel which is located in the drill. The fluid channel emerges externally by means of a discharge orifice in the flank of a major cutting edge. The cooling channel extends through the drill and can be supplied by means of a supply orifice in the end surface of the tool shank with coolant or more generally with a fluid which is suitable for cooling and/or lubrication during the drilling process. The coolant can be a fluid, a gas or a mixture of these substances.
2. Background Information
One disadvantage of known drills is that the fluid which is discharged from the flanks of the major cutting edges only reaches the actual site of the drilling, namely the major cutting edges, the minor cutting edges and the cut surfaces, as well as the faces or rakes and also the back of the drill. In particular on the major and minor cutting edges, the cutting and deformation work being performed generates a large amount of friction and consequently high temperatures. To ensure that sufficient fluid is available at these sites, correspondingly large quantities of fluids and high pressure are necessary. The use of large quantities of fluid also entails high costs for the disposal of the fluid.
Recently, a very great potential has been identified in dry machining. However, since not all cutting problems can be solved with 100% dry working, alternate approaches are also being considered which include micro-lubrication. This type of machining can frequently be considered quasi-dry machining, because the problems usually encountered during wet machining (coolant and lubricant oil supply, equipment costs, cleaning etc.) preferably do not occur.
As a rule, in these systems the lubricant (generally oil) is applied to the work site (drill bit, saw blade) by means of nozzles. During drilling, however, problems occur with this solution, because the lubricant can only be applied when the drill is outside the boring. If the lubricant were to be introduced through the spindle and through the drill, and an internally cooled drill were used, the problem could be solved somewhat more successfully. Here again, the problem arises that as a result of the long path of the lubricant, more lubricant is required simply to fill the lines than would be required to solve the problems strictly related to the chip removal. According to information from a manufacturer, approximately 100 ml per shift is required to lubricate a tool externally.